The invention relates generally to respirators and more particularly to respirators that also assume a measurement task such as the determination of the functional residual capacity of the lungs
Respirators are usually operated with a mixture of oxygen and air. Laughing gas is also added as another gas in inhalation anesthesia apparatus. These gases are made available from a central gas supply unit in medical treatment rooms by plug type couplings. These supply the respirator with the necessary gas in the treatment rooms. Besides the pure respiration, respirators nowadays also increasingly assume measurement tasks, e.g., the determination of the functional residual capacity of the lungs during artificial respiration. A test gas is mixed with the breathing gas for this purpose, and this test gas is supplied newly for each breath. With the knowledge of the patient-specific residual capacity, the respiration parameters can be better adapted to the patient. As a consequence of this, the respiration can be carried out in a gentler manner. A respirator for determining the functional capacity has become known from EP 791 327 A2.
The test gas is fed in usually from commercially available compressed gas cylinders. The cylinders must be fastened on a separate cylinder cart because of their size. Such a cylinder usually used has, e.g., a volume of 10 L. This makes handling of such cylinders difficult in routine clinical operations. The measurement tasks must be performed only at certain points in time within set time periods. The cylinder cart with the compressed gas cylinder is not needed during the rest of the time. If measurement tasks are performed on different patients, the cylinder cart must be transported to another patient bed. Only comparatively small volumes of the test gas are needed for the measures that usually need to be performed, so that it is not necessary to keep ready an excessively large gas reserve at the respirator.
Besides helium as the test gas, heptafluoropropane is also suitable; in addition, this has the advantage of being able to be stored in the liquid form. Heptafluoropropane has, e.g., a vapor pressure of 3.9 bar absolute at a room temperature of 20xc2x0 C. and a vapor pressure of 7 bar absolute at 40xc2x0 C. Due to the liquid storage, a large gas volume can be accommodated in a comparatively small compressed gas cylinder.
A basic object of the present invention is to provide a storage medium with an adapter to provide an additionally needed gas for a respirator in a simple manner and to provide a process for storing a gas for a respirator.
According to the invention, a device is provided for releasing a gas to a respirator. The device includes a compressed gas cylinder which contains the gas. A metering valve is provided that can be opened by pressure. The metering valve includes a valve body (e.g., tubular) letting through the gas and with a collar surrounding the valve body. A cylinder adapter (1, 100) is provided that has a locking mechanism for fastening on the collar and a cylindrical wall part in the area of the valve body. A pressure body can be connected to the wall part via a connection element in such a way that a stroke movement is possible. The pressure body has a pressure piston for actuating the valve body and a gas channel for drawing off the gas to the respirator. A predetermined breaking point with reduced strength properties on the cylinder adapter is employed to destroy or functionally negate the locking mechanism during the removal of the cylinder adapter from the collar.
According to another aspect of the invention, a process is provided for storing a gas for a respirator. A compressed gas cylinder is used as the storage medium for the gas. A metering valve that can be opened by pressure is provided with a tubular valve body and with a collar surrounding the valve body. A cylinder adapter is provided with a locking mechanism such that the locking mechanism can be fastened to the collar. A predetermined breaking point with reduced strength properties is provided on the cylinder holder. The locking mechanism is destroyed during the removal of the cylinder adapter from the collar.
An advantage of the present invention is essentially that due to the combination of a cylinder adapter with a commercially available compressed gas cylinder, as is used, e.g., in spray cans, an inexpensive gas reservoir is made available, which can be connected to the respirator in a simple manner. The cylinder adapter needed for the adaptation is fastened to a collar located in the area of the valve element of the compressed gas cylinder by means of a locking mechanism. In commercially available spray cans, a protective cap, which protects the valve element from damage or accidental operation, is normally located on this collar. The cylinder adapter is provided according to the present invention with a predetermined breaking point, which has a reduced resistance cross section and is intended to destroy the locking mechanism during the removal of the cylinder adapter from the collar. It shall be achieved by means of the predetermined breaking point that the cylinder adapter cannot be fastened to another compressed gas cylinder after removal from the compressed gas cylinder and an undesired gas cannot be fed to the respirator as a result. The cylinder adapter is normally fastened to the collar of the compressed gas cylinder prior to the filling of the compressed gas cylinder. It can be achieved by means of the cylinder adapter that only a certain counterpiece, a pressure body, can be connected to the cylinder adapter in order to remove gas for supply to the respirator. The metering valve of the compressed gas cylinder is opened by pressing the tubular valve body. The pressure body is displaceable for this purpose in relation to a cylindrical wall part on the cylinder adapter in the form of a stroke movement and it has a push rod, which actuates the valve body. Depending on the positioning of the push rod in relation to the valve body, gas can be removed from the compressed gas cylinder. The compressed gas containers used according to the present invention are especially inexpensive because they are manufactured in large lots for different applications.
The connection element is advantageously designed as a bayonet catch, with which the stroke movement can be carried out in a simple manner.
It is especially advantageous to provide the bayonet catch with a park position, which is used to ensure that the pressure body is nevertheless connected to the cylinder adapter with the metering valve closed. The grooves of the bayonet catch are provided for this purpose with depressions used as a locked position for the park position in the areas in which the pin-shaped counterpiece is introduced.
In the area of the collar, the locking mechanism advantageously comprises a support on the cylinder adapter and a counterpiece, which is located at a support ring that is arranged in an annular space between the compressed gas cylinder and a grip shell on the cylinder holder. The grip shell extends, beginning from the collar of the compressed gas cylinder, over a partial area of the outer wall of the compressed gas cylinder.
The predetermined breaking point is arranged according to the present invention in the form of a circular notch in the connection area between the cylindrical wall part, at which the pressure body is located, and the grip shell. The cross section of the wall is reduced by the notch in this area of the cylinder adapter, so that the locking mechanism is destroyed in the area of the predetermined breaking point when the cylinder adapter is pulled off from the collar.
It is particularly advantageous to manufacture the cylinder adapter from two symmetrical housing shells and to be connected to one another via a sealing band. The sealing band is dimensioned such in terms of its strength properties that it will be torn up when the cylinder adapter is pulled off from the collar of the compressed gas cylinder.
According to an advantageous process for storing a gas for a respirator, a compressed gas cylinder is used as the storage medium for the gas, which has a metering valve that can be opened by pressure with a tubular valve body and with a collar surrounding the valve body. A locking mechanism located on a cylinder adapter is designed such that the locking mechanism can be fastened to the collar, and a predetermined breaking point is provided on the cylinder adapter such that it breaks when the cylinder adapter is removed and thus destroys the locking mechanism. It shall be achieved as a result that the cylinder adapter cannot be subsequently mounted on another compressed gas cylinder.
An exemplary embodiment of the present invention is shown in the figure and will be explained in greater detail below. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.